We divide 640091 by 80
We're looking to find how many times 80 goes into 640091.

On to step 1:
6 divided by 80 is 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 80

Let's proceed to step 2:
80 can be fit into 64 0 times, resulting in a remainder of 64.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 64 leaves us with 64.
Append the next digit (0) from the dividend to 64 and continue with: 640 / 80

Step 3:
When dividing 640 by 80, we get 8 with a remainder of 0.
Write down 8 as next digit of the result. 
Result so far: 8.0
If we subtract 640 from 640, we get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 80

Going ahead to step 4:
If we divide 0 by 80, we get 0 and a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 80.0
Deduct 0 from 0 and we're left with 0.
Append the next digit (9) from the dividend to 0 and continue with: 9 / 80

Step 5:
If we divide 9 by 80, we get 0 and a remainder of 9.
The next digit of our result is 0. 
Result so far: 800.0
If we subtract 0 from 9, we get 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 80

Advancing to step 6:
80 goes into 91 1 times with a remainder of 11.
Record the quotient 1 as the next digit in the result. 
Result so far: 8001.0
Subtracting 80 from 91 leaves us with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 7:
80 can be fit into 110 1 times, resulting in a remainder of 30.
Use 1 as the next digit of our solution. 
Result so far: 8001.1
If we take 80 away from 110, we end up with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

On to step 8:
80 goes into 300 3 times with a remainder of 60.
The next digit of our result is 3. 
Result so far: 8001.13
If we take 240 away from 300, we end up with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Moving on to step 9:
The number 80 fits into 600 7 times, leaving a remainder of 40.
The next digit of our result is 7. 
Result so far: 8001.137
Subtract 560 from 600 to get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Step 10:
80 goes into 400 5 times with a remainder of 0.
Record the quotient 5 as the next digit in the result. 
Result so far: 8001.1375
If we subtract 400 from 400, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 11:
The number 80 fits into 0 0 times, leaving a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 8001.1375
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 12:
80 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 8001.1375
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 8001.1375 and a remainder of 0.0.